:: rem 注释语句，一般用来给程序加上注解，该命令后的内容不被执行，但能回显；当 echo on 状态时，rem指令的内容会被打印出来，可以理解成日志的级别
@echo on
echo rem order
rem this is a notice, it will be show 
@rem this is a notice, it will not be show, because --> @

pause

